SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe3297f0150ed57e272703d543f88e5c513562b2bc5abcfbf59367e472ad1398' 
  AND token = 'HGjusViZybqJF/V+ZkauBxvuJgDvy3nxX2miY2AYEnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}